Finish for ferrous articles



Allg- 1933- A. w. MACHLET FINISH FOR FERROUS ARTICLES Filed April 21, 1930 v INVENTOR Jlvlal h wMMhw: BY

ATT RNEY Patented Aug. 8, 1933 UNITED STATES FINISH FOR FERROUS ARTICLES .7 Adolph W. Machlet, Elizabeth, N. J.

Application April 21, 1930.

8 Claims.

- This invention pertains to ferrous articles of all forms, shapes, sizes and analyses which require a superior permanent finish, and also ways and means to produce same.

A broad object of this invention is to combine two or more conventional heat applied finishes to produce a superior finish. Other broad objects are to provide an improved process and an improved apparatus for the practice of such im- 0 proved process.

Another object is to provide a hard and durable finish uniformly applied upon ferrous articles wherever desired: said finish being unaffected by atmospheric temperature or humidity even when exposed to the weather.

A specific object is to apply such a finish to small ferrous articles, hardware and parts, and thus in some cases to enable brass articles to be advantageously replaced with such ferrous articles, thus providing superior strength, or economy, or efficiency, or longer life, or perhaps two or more of said superiorities.

Referring to the accompanying drawing:-

Fig. 1 is a diagrammatic showing of a furnace apparatus.

Fig. 2 is a perspective of an article of ferrous material contained in said apparatus.

The numeral 1 indicates any furnace which may be, for instance, the type shown in my United States Patent No. 1,745,104. Furnace 1 is provided with burners 2 to heat the closed retort 3, .which has a cover 5, and a discharge pipe 7 equipped with discharge valve '9 to regulate the discharge of waste gases.

At the opposite end of the retort 3,.a stufiing box llis indicated, which is designed to permit retort 3 to be rotated for tumbling the work. The stuffing box 11 is designed to rotate freely upon the intake pipe 13 to which it is connected.

I The members above described bearing the numerals 1 to 13, inclusive, are conventional.

Intake pipe 13 is provided with three branches, 15, 1'7, and 19, having valves 16, 18, and 20, respectively, which are closed in the indicated position. 0

Within the retort 3 is indicated in dotted lines any small object 23 of iron or steel or the like which is to be treated.

The retort 3 is first heated to from 900 to l250 Fahrenheit, and then the valve 16 is opened permitting ammonia gas to fiow into the retort 3 from pipe which is connected to a conven tional source (not shown) of such gas under light pressure. The ammonia gas is allowed to 5 fiow for a period of from two to sixteen. hours,

Serial No. 445,981

thus nitrogenizing the object 23 in a conventional manner. The length of time and the exact temperature during'the nitrogenizing operation being regulated according to the quality and depth of the nitrogenized finish desired upon the object 23;

Upon the completion of the nitrogenizing operation as above described, the valve 16 is closed and the ammonia gas shut off. Thereafter valve 18 is opened and a flow of air under light pressure from a source not shown, through pipe 1'7 into retort 3 is permitted for a period of from fifteen minutes to half an hour or longer at a retort temperature of from 800 to 1250 Fahrenheit. This operation causes an-oxidization of the surface of the nitrogem'zed finish on object 23, producing a dark grey finish which is suitable for some articles and has great resistance to rust and discoloration. Apparently, there is some reaction brought about by the oxidization of the nitrogenized surface at the temperatures above mentioned which brings about an unexpected improvement in the appearance and eifectiveness of the coating.

Upon the completion of the oxidization op'eration, valve 18 is closed and the fiow of airthrough pipe 17 stops. Article 23 may then be removed for use or a further operation applied to it before removal. The further operation consists in the application of what is known as a carbonia or gun-metal finish to the object 23, which may be applied at a retort temperature of from 600 to 800 Fahrenheit for from three to eight hours. The carbonia finish is effected by opening valve 20 in pipe 19 and permitting hydrocarpm oil to fiow into the retort a drop at a time until the carbonia finish is completely applied and the object 23 assumes substantially the appearance of a conventional gun-metal finished article.-

Inthe apparatus as shown and described, the several operations are performed successively in one furnace, but if more convenient, the several operations may be successively performed in two or more furnaces. v

I have found that in some cases the above described oxidizing operation may be omitted with advantage and there may also be some advantage in certain work for omitting the nitrogenizing operation. However, the finish which may be applied as above is capable of application to a large variety of conditions and work, and may be adapted thereto by careful observation and adjustment of the various factors above described. Any one of the three above described operations may be omitted and the other two will combine to ferrous articlw, which consists of nitrogenizeffectively for certain classes of work.

I claim:-- v 1. A new article of manufacture consisting of I a ferrous metal object provided with a combined finish including a nitrogenized foundation, furnace oxidized to a uniform dark gray color and glm-metalized.

2. A new article of manufacture consisting of a ferrous metal object provided with a combined finish including a nitrogenized foundation, furnace oxidized to a uniform dark gray color.

3. A new article of manufacture consisting of a ferrous metal object provided with a combined finish including anammonia nitrogenized foun dation, and gunmetalized. v

4. The process of applying an improved finish to ferrous articles, which consists of nitrogenizing, furnace oxidizing to a uniform dark gray color and gunmetalizing same.

5. The process of applying an improved finish ing and furnace oxidizing same to a uniform dark gray color.

6. The process of applying an improved finish to ferrous articles, which consists of ammonia nitrogenizing and glmmetalizing same.

7. A new article of manufacture consisting of a ferrous metal object provided with a combined finish including a niin'ogenized foundation-applied within the temperature range of from 900 to 1250 Fahrenheit and a gunmetali'zed finish applied on the foundation within-the temperature range of from 600 to 800 Fahrenheit.

8. The process of applying an improved finish to ferrous metal objects which consists of first applying a nitrogenized foundation within the temperature range of from 900' to 1250 Fahrenheit and a gurmietalized finish thereon within the temperature range below the above and down to not lower than 600 Fahrenheit.

ADOLPH W. MACHLET. 

